This disclosure relates to a magnetically alignable semiconductor chip and a rewiring substrate and a method for magnetically aligning the semiconductor chip and the rewiring substrate.
Semiconductor packages in which the semiconductor chip is mounted on a rewiring substrate by flip-chip contacts, such as solder balls or solder bumps, have the advantage that the electrical contact between the semiconductor chip and the rewiring substrate can be provided for all of the contacts essentially simultaneously in a single solder reflow process. Thus, the electrical connection can be provided more quickly than by a bond wire process in which the bond wire contacts are produced serially. Flip-chip contacts also have the advantage that the contacts can be provided at the wafer level which increases productivity and simplifies the manufacturing process.
However, it is necessary to accurately align the flip-chip contacts with the contact pads of the rewiring substrate in order to ensure a good electrical contact and avoid shorts between neighbouring contacts. This is normally achieved by optical or mechanical alignment methods although magnetic alignment methods, as are known from U.S. Pat. No. 6,049,974, are also known.
These alignment methods have the disadvantage that the accuracy of the alignment is limited. Insufficiently accurate alignment is increasingly a problem as the pitch between the chip contact pads and, therefore, the flip-chip contacts is increasingly being reduced.